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Muffler Bypass causing cat failure???

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7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHMuffler Bypass causing cat failure???

Leading reported evidence

Run with bypass pipes

Performed · outcome unconfirmed

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that performed work without a confirmed outcome: 1

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Performed · outcome unconfirmed
I ran with bypass pipes on my car for nearly a year, on and off the track.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Frequently discussed work

Run muffler bypass

No successful repair reported for this finding.

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Reported fixes: 0
Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

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Suggestion
been running muffler bypass on my GT3 for 9000 miles, no problems.
Original post Read captured discussion
Muffler Bypass causing cat failure???

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Leading evidence: 'Run with bypass pipes' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Run muffler bypass' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 7 captured posts examined · 0 partial discussions

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Run muffler bypass

Suggestion or failed attempt

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Unsuccessful attempts: 1
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Discussions that contain suggestions: 1

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Suggestion
been running muffler bypass on my GT3 for 9000 miles, no problems.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Use bypass pipes, i denied it of course

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

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Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

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Suggestion
Out of the blue they ask me if I ever used bypass pipes, I denied it of course.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Frequently discussed actions (3)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Run muffler bypass

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
been running muffler bypass on my GT3 for 9000 miles, no problems.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Run with bypass pipes

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that performed work without a confirmed outcome: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed
I ran with bypass pipes on my car for nearly a year, on and off the track.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Use bypass pipes, i denied it of course

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

Discussions that contain suggestions: 1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion
Out of the blue they ask me if I ever used bypass pipes, I denied it of course.
Original post Read captured discussion
Muffler Bypass causing cat failure???

Coverage and how to read this overview

Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

7 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261027T013556Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

So it was mentioned in another thread, I just wanted to check who else has experienced this and what the possible explanations are... I�m about to do the bypass pipes but the cat failure has been putting doubt in my mind...

POST 2Original post

i'd like to find out as well. maybe the fabspeed guys can chime in on this.

POST 3Original post

muffler bypass will not cause any light to come on. Cat by pass might.

POST 4Original post

Mine did, I only used them for track weekends(10x), one day a CEL goes on, dealer says it's the cats and fixes it under warranty($$). Out of the blue they ask me if I ever used bypass pipes, I denied it of course. Later,a few guys on this board mentioned the same thing, that's all I know.

POST 5Original post

That is odd, could it be that there is too much flow going through the stock cats that would cause them to fail? how much are new cats?

POST 6Original post

I ran with bypass pipes on my car for nearly a year, on and off the track. I never had a problem.

POST 7Original post

been running muffler bypass on my GT3 for 9000 miles, no problems. if cats fail, time for cat bypass as well!

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